This invention relates to packaging apparatus, and more particularly to apparatus for packaging a product in a tubular bag having its ends sealed closed.
Specifically, this invention relates to an improvement of packaging apparatus as disclosed in U.S. Pat. No. 2,976,657 to Cloud in which a product to be packaged is placed on a web, and the web is formed into a tube around the product and sealed and severed in front of and behind the product to form a bag. In the above-mentioned Cloud patent, the entubed products pass around a so-called rotary turret or wheel. A plurality of clamping assemblies or die sealing units are held stationary in a rest or hold position at one location on the wheel with the wheel rotating relative to the sealing units when the latter are in their hold position. In timed-relation to movement of the portions of the tube between successive products therein, the sealing units are released one at a time from the hold position and are coupled to the wheel for being driven by the wheel. Each sealing unit has a fixed lower jaw and a hinged upper jaw swingable from an open to a closed position as the sealing unit moves from the hold position so as to clamp the tube between the jaws intermediate successive products in the tube. The jaws may be heated so as to heat-seal the tube, or may include other means to otherwise seal the tube transversely across the tube. Also, the jaws may carry a severing blade (or a heated wire) for severing the tube within the seal formed by the jaws thereby to form the trailing end seal of a leading bag and the leading end seal of a trailing bag. The jaws securely grip the web as the die moves with the wheel and thus pull the tube and products therein through the apparatus at the speed of the wheel. In the above-mentioned Cloud patent, sealing units are coupled to the wheel by means of a so-called clutch at one side of each sealing unit.
Other packaging apparatus similar to the above-described apparatus are known which have means for releasably coupling the sealing units to the wheel at both sides of the sealing units. However, in the apparatus shown in the above-mentioned U.S. Pat. No. 2,976,657 and in the above-mentioned similar apparatus, the coupling means sometimes causes the sealing units to cant or cock relative to the wheel which in turn results in an oblique seal being formed or in the jaws closing on a portion of the product. Furthermore, this canting or cocking of the sealing units may cause them to stick to the wheel thus preventing their release at the hold position and thus they may be forceably driven into the other sealing units at the rear of the hold position with possible consequent damage to the apparatus.